During an impromptu meeting of the Xindi Council, Degra, frustrated, waits for the full council. After a bit of arguing, he reveals prematurely that while the primary weapon is not ready, he is testing the second prototype in the Calindra system in three days and will broadcast the test back to the Council.

Shran contacts Archer

Meanwhile, the Enterprise is hot on the trail of the Xindi primary weapon (thanks to Gralik's sabotage). EnsignHoshi Sato and Sub-commanderT'Pol have been able to reconstruct 30 percent of their database which was deleted by D'Jamat. The weapon is inside an exceptionally intense anomaly field, which they can't go around. CaptainArcher orders the ship forward, with T'Pol guiding, however, she doesn't have enough data and soon the anomalies become too erratic. The ship is nearly destroyed, however, at the last moment, an unidentified ship locks on with a tractor beam and pulls Enterprise to safety. When Archer contacts the ship to express his gratitude, he is speechless to see Commander Shran looking back at him on the viewscreen.

Shran comes aboard the ship and explains that he came to the Expanse as an ally to help stop the Xindi from destroying Earth. Shran phrases his speech so that it seems that the Andorians are using the occasion to show moral superiority to the Vulcans, who have not assisted their allies on Earth despite possessing the resources to do so. He does commend T'Pol's resignation of her commission to help Archer, however. After a moment of hesitation, Archer accepts Shran's offer of assistance, even if out of necessity.

Archer meets Lieutenant Malcolm Reed in the armory to inform him of Shran's tactical officer coming to help. He's hesitant of allowing them access to critical systems, but Archer says they need help. T'Pol soon finds Archer to inform him the Andorian ship has docked, and to suggest posting security teams with each repair crew. Archer feels that will decrease efficiency, and, after more information about the Vulcans' bad experiences with Andorians, admits he doesn't trust them, but feels he can trust Shran.

Andorian engineers and maintenance crews come aboard. Reed and Trip Tucker, taking a break in the mess hall, meet Talas when she enters the room loudly asking the whole crew in the room who Reed is. She makes it clear she doesn't want to be there, and takes jabs at both of them as she reports for ordered duty. Tucker leaves the two to get acquainted. Tucker, back in engineering, eventually finds T'Pol arriving for an an update, having only seen her for their Vulcan neuro-pressure sessions. He says the "blue guys" really know their stuff and that they should be operational in 12 hours. He also remarks T'Pol may be avoiding him, but she assures him she's busy.

Meanwhile, Shran joins Archer for dinner, seemingly excited to work with him. He brought Archer some bottles of Andorian ale and, opening one, toasts to a quick victory. Through talking, Shran informs Archer he volunteered for the assignment, through his experience and also due to his unpaid debt to Archer for helping with the Vulcan conflict. He also alludes to future cooperation between Humans and Andorians.

In the armory, Reed is aligning some relays with Talas only watching. Reed is dismissive toward her, clearly not wanting her help, despite that she brought equipment that can help. Sarcastically, she offers to get him coffee, and he accepts, which prompts her to take her leave. She notes as she goes that she's not there to steal secrets, and also that the weapons are inferior to what she knows anyway. Reed takes offense and goes back to working, however, when she notes that he forgot a step in the process, he pauses and apologizes. He'll get her some coffee and they'll work together.

With the Enterprise in shape, and Shran on their bridge, they head for their target. They arrive just outside the Calindra system and, with the Andorians' more advanced sensors that won't give away their position, they find four ships, all Xindi.

It appears the uninhabited moons are heavily scarred. Archer concludes that this is a proving ground, not unlike Bikini Atoll, which means they don't have much time. Shran notes the defenses are too much for a full assault, and he's not ready to risk his ship when they don't know if the weapon is there. Archer agrees, and wants more information.

Shran goes back to his ship, and is approached by Tucker for one of their advanced antimatterinjectors. Shran is hesitant, as that is sensitive information and it remains to be seen to what extent they are allies. Shran tells Tucker he knows about the death of his sister, and relates through his losing of a brother in border disputes with the Vulcans. Tucker says he doesn't yet want revenge, just wants to prevent the Xindi from finishing what they started. Shran promises the injector before he goes.

Degra, ready for the test, contacts the anxious Xindi Council again. Degra orders final calibrations and the weapon is launched. However, a proximity alarm sounds and Degra cancels the test, unable to identify the ship (not aware of the Andorians). He answers a hail from Shran, who is pretending to be with the "Andorian Mining Consortium" and searching for a valuable mineral called "Archerite." Degra is not amused and orders the Kumari to stop scanning the weapon and leave the system or else be fired upon. Shran, in character, concedes and ends the communication. Archer and T'Pol, who have hidden on the Kumari's bridge, observed the whole thing. With detailed scans in hand, the Kumari returns to Enterprise. T'Pol deduces that this test weapon is similar to the one that attacked Earth, but not large enough to destroy an entire planet. Shran notes that this is not the final weapon, so it's not absolutely critical they destroy it, rather, they could measure the results of the weapon themselves. Archer intends to steal it, so Starfleet can better find a defense.

The crew focuses on repairs to the ship. Talas and Reed work together, though when it comes to a point that they need the weapons frequencies, Reed politely keeps that to himself by completing it on his own. They talk a bit about their similar family histories, being military families, and Talas notes his father, while earlier probably disappointed in Reed's choice, would be proud now that he is fighting for the survival of their race. Reed goes to complete the rest of the work, leaving Talas who decides to examine the device they fixed on her own.

The crew of Enterprise is able to watch the Xindi test via a relay from the Kumari's more advanced sensors. The crew members are horrified to see the moon split in half by the weapon.

The Xindi Council is disappointed at the results, as the moon was supposed to be more decimated, and wants answers. Degra was forced to shut the weapon down prematurely, and insists he needs time to analyze the data to decide how to proceed. Dolim, furious with Degra for this setback, exclaims that every failure puts them at further risk. On the Enterprise, T'Pol also determines that the weapon test was a failure. Archer, chuckling, is gratified that Gralik has kept his promise to sabotage their weapon. Right now, the weapon is too hazardous to approach. Archer wants to take it into the ship's launch bay, but T'Pol does not believe the weapon can be brought aboard due to lethal radiation it is emitting. At this point, Shran offers to steal the weapon and store it in the Kumari's (better shielded) cargo bay until it is safe to transfer it to Enterprise.

Archer is immediately suspicious of Shran's motivations for this uncharacteristically altruistic offer, which leads to a confrontation. Archer accepts Shran's offer, but only on the condition that he be allowed to command the Kumari during the retrieval. Shran grudgingly agrees.

Meanwhile, Talas and Reed have come to an understanding and are working together quite nicely, even getting phase cannon efficiency up to 94%. Reed mentions that Talas' talents would be appreciated in Starfleet, and Talas retorts that Reed should consider joining the Imperial Guard if he ever tires of exploring. Later, Reed catches Talas working on the sensor array without reason, but pretends to believe her flimsy excuse.

Shran, back on his ship, has an ominous conversation with an Andorian general, during which he questions his mission and asks if it is worth making enemies of the Humans when they could take the chance to form an alliance instead. The general dismisses it, noting a fondness for the "pink skins" in Shran's argument.

The two ships make their move. Enterprise enters the system first, drawing out two Xindi-Reptilian ships and successfully damaging their engines. While those ships are distracted, the Kumari enters the system from the opposite side and tractors the prototype into its cargo bay. Degra falls for the tactic, finding out too late that the ships are working together.

After the surprisingly successful raid, Archer orders the Kumari to rendezvous with Enterprise. Talas looks to Shran, who then ends his cooperation, ordering a course for Andoria. Their real intention apparently was to steal the Xindi test weapon for themselves.

Archer is furious, but Shran tries to defend his actions. First, Shran emphasizes that his loyalty is with the Imperial Guard, and not with the "pink skins." Shran reveals that the Imperial Guard wants to keep the Xindi weapon for themselves, as a weapon to potentially be used against the Vulcans. Archer states that Enterprise will fight for the weapon, but Shran counters that Talas has secretly sabotaged their sensor array and that Enterprise would not be able to find them. Furious that the Andorians would endanger Earth over a border dispute with the Vulcans, Archer punches Shran in the jaw, drawing blue blood from his lip (noting that it settles his own personal debt from their first encounter). Shran orders Archer dropped off in an Andorian escape pod equipped with a navigation beacon so Enterprise will know where to find him. The Andorians begin making detailed scans of the weapon. When Shran informs his superiors of the mission's success, he is visibly upset and refuses a commendation.

When Enterprise arrives to pick up Archer, it is revealed that Lt. Reed had been closely watching Talas and her sabotage attempt was unsuccessful. When Enterprise catches up with the Kumari at an anomaly field, Archer hails Shran and reveals that T'Pol has decrypted the weapon's arming protocols; Archer threatens to detonate the weapon while it is in Shran's cargo bay, but Shran believes he is bluffing. Shran asks Archer why he would do this, and Archer counters that he can not take the risk that the Andorians would use the weapon against the Vulcans. Shran questions Archer's loyalty to the Vulcans, and Archer senses that there is no compromise to be had. With no other options, Archer orders the weapon armed, and it begins to overload while still on board. Shran orders the weapon jettisoned, and it explodes in space. Enterprise is far enough away to avoid damage, but the Kumari is heavily damaged. Archer offers help, but Shran graciously refuses. When the ships part ways, the Andorian vessel is limping away on auxiliary power.

Just before it leaves sensor range, someone aboard Kumari sends a covert transmission to Enterprise, consisting of the detailed scans of the Xindi weapon. Archer orders the scans sent to Starfleet, and offers to share some Andorian ale with Tucker and T'Pol.

- Commander Shran, to Archer, after rescuing Enterprise from certain doom inside of an expanding anomaly

"Your world is in jeopardy, and where are your friends, the Vulcans? Where is their mighty fleet? They couldn't even spare one officer! She was forced to abandon her career to remain on your ship – a remarkably selfless act... for a Vulcan. But we've come to your aid. We've come into the Expanse when they refused. We're here to help you."

- Shran, to Archer and T'Pol, in response to the captain's query about his intentions

"Well, I'll let you two get acquainted."

- Tucker, to Reed and Talas, after witnessing their first meeting

"So... how did you get picked for this assignment?"
"I volunteered. It made sense. I've had the greatest amount of contact with pink... with Humans, and the last time we met you helped my people avert a war. I don't like unpaid debts."
"We keep doing each other favors."
"Isn't that how alliances are born?"

- Archer and Shran

"How long until we have warp?"
"I would say at least two days, but, uh, the blue guys really know their stuff!"

- T'Pol and Tucker

"Is there anything else I can get you... some coffee, perhaps?"
"Oh, that'll be lovely!"

- Talas and Reed

"The last time I saw weapons like these was during my early tactical training."
"I'm sorry I wasted your time on our primitive systems."
"Not at all... I found it nostalgic."

- Talas and Reed

"Lieutenant Talas... I apologize if I've been rude. Why don't I get us both a cup of coffee and we can align these relays... together."

"For two hundred years, all that's kept them from invading Andoria is the threat of massive retaliation. With a weapon of this magnitude at our disposal, they wouldn't dare attack us."
"You're putting Earth at risk because of a border dispute with the Vulcans?!"
"We disrupted the Xindi test, took their weapon. We may have helped save your world!"
"I guess I'm not familiar with the Andorian concept of help!"

- Shran and Archer

"You like to talk about repaying debts. I've owed you that for a long time."

Despite the destruction of the prototype well before the Andorians could make any use of it, the Vulcan High Command was told that Shran had been successful and that the Imperial Guard was, in fact, studying it for their own purposes, and a year later would use their supposed possession of the weapon in order to launch a "preemptive" invasion.

The kemocite with the modified radiolytic signature in it from "The Shipment" is finally detected and tracked down in this episode, six months after its inception.

When Shran contacts the Xindi, he pretends to be a scout from the "Andorian Mining Consortium". This could be a reference to the non-canon video game Star Trek: 25th Anniversary, which was the first (and only) source where the Consortium was mentioned. However it is not made clear in that episode that the Consortium really existed; it could be an invention improvised by Shran.

Shran also foreshadows the creation of the Coalition of Planets when he talks about forming alliances, although here it is only between Andorians and Humans, with Vulcans pointedly absent.

Guest composer John Frizzel composed the music for this episode. He went on to compose the music for the episode "The Forge".

Shran justifies taking the Xindi weapon by claiming that Xindi technology would deter the Vulcans from attacking them, however it later has the opposite effect, when in "Kir'Shara", V'Las uses the (false) information that the Andorians have acquired Xindi technology to justify an invasion of Andoria.

As Enterprise passes through the field of spatial anomalies, the anomalies begin to merge, forming anomalies large enough to fully engulf Enterprise. This foreshadows the discovery of the much larger trans-dimensional disturbance in "Harbinger".